Polyneuropathy Pt 1: GBS & CMT

Question 1

Briefly define the term Guillain-Barré Syndrome (GBS).

Answer 1

an acute and rapidly progressing peripheral polyneuropathy.

Question 2

List the factors that predispose to GBS

Answer 2

Aetiology is unknown.

Some factors are thought to predispose to GBS: 
o	respiratory infections 
o	swine flu vaccine
o	Hodgkin’s disease 
o	surgery

Question 3

Describe the clinical manifestations of GBS

Answer 3

Motor neuropathy:
o	is predominant
o	is rapidly progressing
o	may paralyze all voluntary muscles 
o	bilateral facial paralysis is common and characteristic
Sensory neuropathy:
o	usually milder c.f. motor abnormalities
o	typically observe: tingling paresthesia 
        in hands and feet
o	can be profound and dominant 
        clinically (uncommon)
Pain: common
Autonomic dysfunction: this may 
        manifest as:
        hypertension cardiac arrhythmias

Question 4

Describe the typical clinical course of GBS.

Answer 4

GBS is a rapidly progressing condition.
The patient is usually an individual who suffered a mild respiratory infection in the preceding 2–3 weeks.
GBS develops as follows:
a) painless onset of mild weakness in the lower extremities
o the patient often does not notice the weakness unless walking uphill, climbing stairs etc.
o may also have tingling parasthesia in toes and fingers
o deep tendon reflexes are diminished
b) the weakness becomes more profound
o this occurs over a few days after the onset of the weakness
o often extends to involve the upper limbs and eventually the face (this is known as Landry’s ascending paralysis)
o deep tendon reflexes dissappear
o may have loss of proprioception in arms and legs
o breathing and swallowing becomes difficult
o typical clinical examination findings at this stage:
o symmetrical motor weakness (both proximal & distal muscles of all limbs)
c) The weakness progresses for several days to a couple of weeks, and finally stabilises, remaining
constant for a varyable period of time.
Recovery then begins (in 85% of patients healing is complete within several weeks – months).

Question 5

Discuss the diagnosis of GBS.

Answer 5

Lab tests cannot specifically diagnose GBS, Therefore Dx will rely on disease pattern recognition. SSx can be variable making early dx hard.

Question 6

Discuss the treatment of GBS.

Answer 6

Treatment is mainly supportive. 
Hospitalization is usually need because of the need for: 
o	respiratory support  
o	cardiovascular monitoring 
Plasmapheresis can hasten recovery.

Question 7

Discuss the prognosis of GBS

Answer 7

85% of patients recover after a few weeks – months.
Little or no recovery occurs in a minority of patients.
5% of patients die. Most deaths are mainly due to cardiac arrhythmias.

Question 8

Discuss the complications of GBS.

Answer 8

Headaches and papilledema occurs late in the disease in patients with very high CSF protein levels.
Proposed mechanism: plugging of arachnoid villi by excessive protein levels

Question 9

Briefly define the term Charcot-Marie-Tooth disease (CMT)

Answer 9

a) Charcot-Marie-Tooth disease (peroneal muscular atrophy) is a group of hereditary sensorimotor neuropathies
b) It affects motor nerves and sensory nerves of the lower legs
c) Lower limb weakness and atrophy are key clinical features

Question 10

Discuss the Epidemiology and Classification of CMT.

Answer 10

• Charcot-Marie-Tooth disease is the most common hereditary neuropathy - affects 1 of 2,500 people.
• There are two main types of CMT and over 50 subtypes of the disease

Question 11

Discuss the Etiology of CMT

Answer 11

Most types of the disease are inherited as an autosomal dominant trait

Question 12

What is the basic pathological process occurring in CMT?

Answer 12

Depending on the type, the following may be affected:

• myelin sheath (demyelination)
• axons

Question 13

Discuss the clinical picture of Type 1 CMT

Answer 13

Symptoms begin in middle childhood
Early:
i) weakness begins in the lower legs
ii) inability to flex the foot (footdrop)
iii) calf muscle atrophy (stork leg deformity)
Later:
i) atrophy of hand muscles
ii) centripetal loss of vibration, pain, & temperature sense in hands & feet. The disease progresses slowly and does not affect life span

Question 14

How is CMT diagnosed?

Answer 14

Based on:
Clinical presentation i.e.: 
      i)	distribution of weakness 
      ii)	age of onset 
      iii)    presence of foot deformities (high arches and hammer toes)
Family history 
Nerve conduction studies 
Genetic testing